高温法兰密封系统长周期运行失效机理及设计准则研究

Aiming at the challenging issues of degradation mechanism of sealing performance and reliable operation of elevated temperature flange sealing systems under long period operating conditions, with the goal of establishing the leakage-control based design criteria of elevated temperature flange sealing systems, three key questions will be investigated during this research work. Firstly, to obtain the attenuation law of the sealing performance of the flange connection after long period service, and to form the relationship between the compression force and the seal leakage rate under different service conditions, during studying on sealing mechanism and creep relaxation performance of the elevated temperature flange system. Secondly, to study on the damage evolution law and failure mechanism of the flange system under high temperature and temperature fluctuation, and to get the multi mode failure mechanism of high temperature flange sealing system and the influence of creep on the system performance. Finally, to establish the leakage-control based design criteria of the elevated temperature flange sealing system, by the aid of the study of leakage prediction model, the seal condition monitoring and the determination of seal failure criterion under different flange system using conditions. Through four years study aiming at the breakthrough on the performance degradation mechanism of high temperature flange sealing system with long period operation, the creep based failure mechanism of high temperature flange joint, the leakage based design criteria of elevated temperature flange joint, it is hoped that the some fundamentals can be established for the safe and reliable operation of elevated temperature flange sealing systems.

围绕高温法兰密封系统长周期运行条件下密封性能衰减机理和可靠运行难题，以建立基于泄漏率的高温法兰密封系统设计准则为目标，重点突破三个关键：通过法兰密封系统的高温密封机理以及系统蠕变松弛规律的研究，获得长周期服役后高温法兰密封性能的退化机理，形成不同服役条件下垫片应力与密封泄漏率之间的关系图谱；进行高温和温度波动时系统的损伤演化规律和失效机理研究，获得高温法兰密封系统多模式失效机制及其对系统性能的影响规律；通过泄漏率预测模型研究、高温法兰运行状态监测以及法兰系统不同使用条件下的密封失效判据的建立，确定高温法兰基于泄漏率的设计准则。通过四年研究，争取在高温法兰密封系统长周期运行时的性能演化机理、基于蠕变的高温失效模式和基于泄漏率的高温法兰设计准则等方面取得突破，为高温法兰安全可靠长周期运行奠定基础。

围绕高温法兰密封系统长周期运行条件下密封性能衰减机理和可靠运行难题，通过研究高温及温度波动条件下法兰密封系统各元件蠕变松弛及失效机理，获得长周期服役后法兰连接结构密封性能的衰减规律，同时获得了温度-压力-垫片选型-接头材料配合等参数影响下，垫片应力和泄漏率的关系图谱。通过研究法兰密封系统高温失效主要机制，获得法兰偏转失效、法兰或螺栓强度失效、垫片回弹失效、螺栓蠕变松弛等不同失效机理下法兰接头的表现及其对密封性能的影响，并根据高温法兰密封系统主要失效机制及其对密封性能的影响以及长周期运行的高温法兰密封状态监测数据分析，建立并完善高温法兰泄漏率预测模型。通过泄漏源特性和泄漏危害分析，建立高温法兰密封失效判据，最后形成基于泄漏率的高温法兰密封系统设计准则。课题研究成果在高温法兰密封系统长周期运行时的性能演化机理、基于蠕变的高温失效模式和基于泄漏率的高温法兰设计准则等方面取得突破，为高温法兰安全可靠长周期运行奠定基础。